1. Field of the Invention
The present invention relates to medical systems and devices. More specifically, the present invention relates to catheter introducers with plastic sleeve assemblies, and to methods of injection molding sleeve assemblies with a single step.
2. Description of Related Art
There has been a longstanding need in the medical profession for devices and methods by which fluids can be injected into the body or “aspirated,” or removed from the body. Due to the emergence of advanced catheter-related technologies, a larger number of medical procedures that have historically required surgery can now be performed intravenously. Procedures such as angioplasty and exploratory surgery can be carried out without making any incisions other than the puncture necessary to access a blood vessel and insert a catheter. Thus, there is a renewed need for safe, reliable, and comfortable methods of inserting and maintaining a catheter within a blood vessel.
A “catheter introducer” is a device that can be used to access a blood vessel for insertion of a catheter. A catheter introducer typically includes a “cannula,” or needle that is used to puncture the patient's flesh and form an opening in the wall of the blood vessel. The cannula may have a hollow bore through which blood or other fluids can flow. A catheter introducer may also include a plastic sleeve assembly designed to fit around the cannula. A sleeve assembly may be used to maintain the opening in the wall of a blood vessel while the cannula is withdrawn. A catheter can then be inserted into the blood vessel through the sleeve assembly. Once the catheter has been inserted, the sleeve assembly can be removed from the blood vessel, along the catheter.
Although the use of the catheter introducer provides some improvements in the catheter insertion process, several problems remain. Many sleeve assemblies have tips that lack the precision to maintain a close fit over the cannula; hence, they irritate the walls of the blood vessel upon insertion into the vessel with the cannula. Some sleeve assemblies have a bent sleeve or a non-uniform wall thickness, and are therefore subject to puncture by the cannula or to leakage through a thin-walled portion the sleeve.
Furthermore, many sleeve assemblies cannot be easily removed from the catheter after they are withdrawn from the blood vessel. Such sleeve assemblies may present an obstruction during operation of the catheter. Indeed, an attempt to remove a sleeve assembly through the use of scissors or the like can cause damage to the catheter.
Some sleeve assemblies are made to split in half for removal from the catheter. Such sleeve assemblies are subject to a number of different problems, including premature splitting (i.e., splitting during assembly with the cannula or during insertion into the blood vessel), breakout (incomplete splitting), leakage through tear seams, and the like.
Additionally, sleeve assemblies are generally somewhat expensive to produce with traditional methods because several manufacturing steps are involved. A tubular sleeve is commonly produced through the use of an extrusion process. The sleeve may be attached to a molded handle/hub piece through the use of swaging or a similar process. The end of the sleeve is then processed in a tipping operation to create a tapered tip of the desired size and shape. The use of such a large number of processes makes the manufacture of sleeve assemblies unduly expensive and time-consuming.
Accordingly, a need exists for an improved sleeve assembly and manufacturing method for a catheter introducer. Such a sleeve assembly should preferably be easy to assemble with the cannula, and should cause a minimum of patient discomfort upon insertion into the blood vessel with the cannula. Additionally, the sleeve assembly should be easily removable from the catheter after withdrawal of the sleeve assembly from the blood vessel. Furthermore, such a sleeve assembly should be inexpensive and easy to produce, preferably with a minimum of manufacturing steps.